These days polymers based on various organic monomers are present almost everywhere around us. They are equally used for exterior as well as interior purposes. For that reason it is very important to make most of these polymers flame retardant to minimize the risk of fires. In the past most common flame retardants were halogenated organic compounds which showed a very high efficiency in flame retardation of polymers. These halogenated compounds act by gas-phase mechanism, which means that in case of fire they decompose and easily release halogen-radicals. These halogen radicals act as a scavenger to trap reactive H*- and OH*-radicals so that there is no heat flow to sustain the flame. Nowadays some of these halogen based flame retardants have been banned because they are environmentally not very benign. Hence there is more than ever a need of novel flame retardants that are able to replace and act like halogenated ones.1 DOPO (9,10-dihydro-9-oxa-phosphaphenanthrene-10-oxide)2 and some derivatives thereof have drawn much attention in the last decade due to their flame retardant properties.3 It is mainly accepted and investigated in detail that these compounds predominantly act by a gas phase-mechanism.4

During combustion they decompose and release low molecular weight phosphorus-containing fragments that are able to scavenge H*- and OH*-radicals.4a,5.
In the literature there are a lot of reports dealing with the synthesis and flame retardant application of alkyl DOPO-derivatives.3,6 
Apart from this, one can also find several reports dealing with the synthesis and application as flame retardant of alkoxy DOPO-derivatives. In contrast to the derivatives mentioned above one could find some publications dealing with amino DOPO-derivatives.7,8 To the best of our knowledge there are only few reports which describe the synthesis and characterization of amino-DOPO derivatives.7h-k Again the synthesis proceeds via a two-step reaction sequence as mentioned before.8

Additionally one can also find a few amino-thio-DOPO derivatives in literature.9 Although phosphinate derivatives of DOPO are commonly known as flame retardants for various polymeric systems, the amino derivatives of DOPO are not well studied as flame retardants. It is known that organophosphorus compounds containing a P—N bond i.e. phosphoramidates exhibit superior flame retardant properties for example on cellulose.10 Hence it would be interesting to develop amino derivatives of DOPO and evaluate them, for their FR efficacy. There are a few patent documents mentioning flame retardant application of amino-DOPO derivatives on various polymeric resin compositions7. But the derivatives reported in these patent documents have not been characterized by appropriate analytical methods. Some alkylamino-DOPO derivatives have also been mentioned in EP 1889878 A1 as possible flame retardant structures. However, in said patent document there is no report on such structures having been prepared nor is any method of their preparation elaborated.11 Furthermore there are amino derivatives of DOPO which have been reported as component in organic light emitting diodes (OLEDs), batteries and azo-dyes.8
